Water level controller circuit

Are you familiar with the basics and the different applications of the 555 timer IC. If not, we recommend you 3 books that provide a very good understanding of the IC and its applications. You can check out the reviews and buy the book from our online store:- 3 Great Books to Learn 555 Timer Circuits and Projects.

Description.

A simple but very reliable and effective water level controller circuit diagram is shown here. The circuit uses 6 transistors, 1 NE555 timer IC, a relay and few passive components. The circuit is completely automatic which starts the pump motor when the water level in the over head tank goes below a preset level and switches OFF the pump when the water level in the over head tank goes above the full level.

Probe D is positioned at the bottom level of the tank while probes A, B and C are placed at full, half and medium levels of the tank respectively. The level sensing part of the circuit is built around transistors Q1, Q2 and Q3. When water level is below the quarter level probes A, B and C are open and the transistor Q1, Q2 and Q3 remains OFF. When the water level rises and touches the probes the corresponding transistors gets biased and switches ON. Resistors R1, R2, R3 limit the bases current of corresponding transistors while resistors R4, R5, R6 limit their collector current. LEDs D1, D2 and D3 provide a visible indication of the current water level.

When the water level goes below medium, transistor Q2 gets switches OFF and its collector goes positive. Collector of Q2 is connected to the base of transistor Q6 and as result transistor Q6 gets switched ON. Transistor Q5 will be also ON because its base in connected to the collector of Q4 which is presently OFF. As a result when the water level goes below medium relay K1 gets energized and the pump is driven. The relay is wired in the latching mode so that even if the water level goes above medium level the pump remains ON so that the tank gets completely filled. For wiring the relay in latching mode one set of N/O contacts is used. When relay is activated these contacts close which forms a short across collector and emitter of Q6. This makes the state of Q6 irrelevant to the operation of the relay and the relay remains ON as long as the transistor Q5 is ON. The only way to make the relay OFF is by switching OFF Q5 and it is done automatically when the water level reaches the full level.

Collector of transistor Q1 is connected to the trigger pin (pin2) of IC1. When the water level reaches full level the transistor Q1 gets switched ON. As a result its collector goes to ground level which triggers the IC1 which is wired as a monostable. The output of IC1 goes high for about 1S. This makes the transistor Q4 ON for the same time and transistor Q5 whose base is connected to the collector of Q4 is switched OFF cutting the supply to the relay. This makes the motor OFF and it remains OFF until the water level again goes below the medium level.

Resistor R8 is a pull up resistor for the trigger pin of the NE555. Capacitor C3 couples the collector of Q1 to the trigger pin of NE555 and facilitates edge triggering whenever the transistor Q1 goes ON. A monostable circuit can be made edge triggered by connecting the trigger signal to the trigger input pin through a capacitor. The capacitor blocks DC and passes sudden changes. The circuit used here is termed as negative edge triggered because the monostable is triggered when ever the trigger input signal falls. R10 and R12 limits the collector current of Q4 and Q5 respectively while R9 and R11 limits their base current. R13 limits the base current of Q6 while D4 is a freewheeling diode which protects the switching transistors from voltage transients.

Circuit diagram.

Water level controller circuit diagram

Probe arrangement diagram

The probes can be arranged as shown in the diagram above. Insulated Aluminium wires can be used as the probes. The probes can be binded on a plastic rod and should be erected vertically inside the tank. The length of the probes wires and the supporting plastic rod must be chosen according to the depth of the tank. Since DC is used in the level sensing section electrolysis will occur in the probes and so the probes require small maintenances in 1 or 2 month intervals. Using AC in the sensing section will completely eliminates the chance of electrolysis and I am presently working on such a circuit. You can expect it soon.

Notes.

Use 12V DC for powering the water level controller circuit.

The relay I used was a 5V/220 ohm relay and that’s why the current limits resistor R12 was added in the circuit. If you use a 12V relay then the R12 can be shorted.

Do not use a relay that consumes 500mA. Maximum collector current PN2222 can handle is 600mA.

Use insulated single strand aluminium wires for probe and they can be arranged in the tank as per the probe arrangement diagram.

Use a holder for mounting NE555.

The circuit can be assembled on a Perf board.

K1 must be a double pole relay.

The load current, voltage ratings of the relay must be selected according to the ratings of the pump motor.

The type number of the transistors used here are not very critical and you can do suitable replacements if any type number is not available.

Most of the components required for this project can be found inside your scrap box.

Power supply for this circuit.

12V DC power supply

A classic 12V regulated DC supply based on 7812 is shown above. A power ON indicator LED is also added in the circuit.Resistor R13 limits the LED current. A small aluminium heatsink can be fitted to the 7812 for better saftey.Small Al heatsinks for TO-220 package are readily available in the market.

We recommend:

Comments

Hi Admin,
It’s a very nice project. Thank you very much for sharing this project. Previously I have done some project using the Arduino.
Now I am doing some project using Microcontroller. I have wished to do that project very soon.

This circuit may not work.
As the water rises, the first transistor may be turned on very slowly and the collector voltage will fall very slowly. The 2u2 will gradually charge via the 100k pull-up resistor and the voltage on pin 2 will never fall to 4v.

I find this circuit very interesting , however I would like to have some modifications to suit my requirement. Can you please help me do that?
I would like to have low level pump starts ,high level pump shuts off and a sump level protector when the level is low the pump turns off.
I also want to use float level switches instead of the probe can you please alter the circuit and mail me so that I can creat this project the way I requested you.
Thanks and regards
Kevin

sir,i have did ds project…using a latching relay of 6 pin..bt second led is glowing when d motor turns ON .cn u send me the total info of d relay used and 5v 220 ohm relay is not available to me.cn i replace it with anyother relay,if not pls cn u say me where is it available…pls sir its urgent.thanku

Sir,
I am complete this circuit and tested in baiket water it is working and I install to overhead tank it is not working properly some problems come when water goes below probe b relay not on and d2 led not fully off it is dem showing after half and one hour relay getting on what can I do please help me sir.

Sir,
Frist I am tested in baiket water it is running good and next I am ueing it to over head tank it is not working properly this problem comeing
I am useing 12volts relay and I shorted R 12 but relay not getting on and when water going below prob b the d2 led was dem but not off and relay not on

Check the probes for correct level. Disconnect probe B and see whether D2 is swishing off. Are you using specified 5 volt 220 ohms relay or something else. No other relays will work in the place. It is a proven circuit it should work check your wiring thoroughly.

I have built the circuit, and when I energize it, two of the LED lights come on and the other LED light stays off. When I energize the circuit, the relay chatters and when I fill the bin with water, the other LED light comes on, but the pump never goes off and the relay continues to chatter. Any ideas?

If you are using 5 volt 220 ohms relay this should not happen. Please check whether the NO (normally open contact when relay is off) is connected for self latching of relay. (bypassing Q6). If these checks are OK check for the correctness of probe connections. Lower most probe should get connected to +12 volts DC. When water level is more than quarter tank Q3 will be on and D3 LED will be lit. When water goes above half tank level Q2 will be on and LED D2 will be lit. Once tank water reaches full level Q1 will be on and LED D1 will be lit and will switch of the pump motor. When water goes below half tank level Q2 LED will go off and pump motor will start.

seetharaman sir can u please tell me what is the use of 1N4007 diode in the circuit???
what is latching mode of the relay???
how to wire the relay in latching mode????
sir please help me out.its very urgent

1N4007 in parallel with the relay to protect the diving element from the back EMF of the relay during switch off. called free wheeling diode. Latching of the relay is sullying the power through its own normally open contact for energising the relay. When relay coil gets an on pulse from the driving element it will switch on and continue to be on through it own NO contact even if the driving element switches off. This is called latching of the relay. to switch off the supply to v\be removed for the next cycle of operation.

Sir,
You have made an essencial & important circuit . In my case I just altered probe B & C .Because there is no use of probe C instead of glow LED, water level never goes down below C because if water level goes below B, Pump will automatically turn ON. so here Q3 always on to glow LED only and never turn OFF. If probe C placed above probe B, it will be perfect. I have placed probes in the following sequence A,C,B & D. A at the top (3/3), C at above half (2/3), B at below half (1/3) and D at bottom(0/3).
Is this Ok?

Sir,can you help me upgrade the circuit. Because there is a time that the motor does not pump water.In that case,there is a possible that the motor be burned.I want to connect a circuit so that when there in no flowing water in the inlet pipe the motor will be automatically turn off after 5 seconds.
THANK YOU

@seetharaman can u design a circuit to control power in different rooms.ie,a circuit whereby a landlord can monitor how tenants consume the power and it can trip the supply when a preset amount of current is exceeded?.THINK ABOUT IT..

Good day sir,
I need circuit diagram for water level controller which should be set in the underground tank which collects the water from the municipal.
that is when the water level rises and attain a particular stage in the underground tank the motor should be switched on and the water if drain the motor should be set off that’s my requirements sir.
Thanks in advance.

I am in process of constructing this circuit for my home. Here you have provided 3 level sensing probes where the middle one just shows that the level of water is above the height of the probe. Now my requirement is to have 5 probes where the first and last for switching OFF and switching ON the motor and remaining 3 LEDs just displays the level of water. Kindly suggest how this circuit can be improved to have that feature.

Sir
my relay is not cutoff when the water is full in tank.and i have use 8-pin DP 5V relay in ckt. Plzz tell me what can in do.and my motor supply is 220V AC.plzz tell me what can i do ?.help me…
Quick rply….

After going through this piece of work I came to realize that ,it is used for a single reservoir but the case Im having is two reservoirs which are connected separately but controlled by one pump. So how can I modify this circuit satisfy my needs? Thanks

Hi, sir sitharaman. I want to use this type of water level controller ckt for water well not in tank. Can i use same ckt in this case when water is ful then pump is on and when water is finished then pump is off.
Plz reply me sir that is important.

well,sir thank you for the circuit…and sir, can u please suggest me the modifications that are to be done in the circuit so that i can use it for different rating loads like 0.5hp, 1hp,2hp…5 hp. kindly help me sir as i am in need of these circuits. -Jagannadh.jagannath.girish@gmail.com

I tried this circuit, there is some error in this. When 12V (batteries) is given to the circuit, middle LED is always glow even other LEDs are glow. Relay is not working, I use 12V DP 8pin relay. Anything wrong in this ckt, help me anyone……….

I tried this circuit. But relay is not working and second LED is always glow even other Led is glow. The 12V 8pin relay is not working I use 12V Dc (batteries) as supply. Is anything wrong in ckt. plz help me…..

Hi i have chosen this to be my project work with small modifications of adding 7 seg. display to the transistor Q1& Q2 through transistors in series to them. can you help with this.
i think this circuit is just fine for domestic water control systems . i want to know if there are any other likely faults, that may present itself in the process of building the circuit.
i will be happy in you can help.

that’s really grade
but can you help me i wnt to do this project but can you tell what is the equipment that i need and the program and the code to do it and explenation ? here is my email : ahmadmahmud18@hotmail.com

hi brother,relay is like a switch it can on and off all electric product.for i hp single phase motor relay should be minimum of 10amp.this circuit is made for 220v moter. neutral point will go direct to motor and phase will go through relay.

hi him kafle,you can use only 8 pin relay which call double poll relay.you are using single poll relay which have 5 pin.in this circuit a double poll relay is required.which have 8 pin.two pin are for coil 12vdc and rest pins are two com and two nc and two no point .you have to use only commen and no pin in this circuit.check with multimeter. one side is holding the relay and other side is for motor to switch on.

Hi Shawn go through my earlier comments
September 19, 2011 at 1:42 pm
Hi Ravi Both probes C and A to be interchanged. C is just to say the electronics is OK with D3 comming on (to indicate also the tank circuit is also healthy and level is minimum). Now read the above description you can understand better. Q2 will start the pumpamd Q1 will stop the pump. Q3 is only for indication nothing to do with automation.

Hi there i think there is a problem with this circuit in terms of explanation how Q1 will be switched ON when the water reaches full level first of all where Q1 is a low level probe … in the explanation it is say ing that “the Collector of transistor Q1 is connected to the trigger pin (pin2) of IC1. When the water level reaches full level the transistor Q1 gets switched ON.” As far as i am seeing Q3 will be switched ON when the water reaches full level it will be biased which is probe C .

sir, kindly mail me the details of project… can i use sp relay in place of dp relay???? is it possible to short the relay and connect the motor directly to the circuit.. pls reply as soon as possible..

hi, thank you , recently i cleaned my sump by disconecting the sensor wires but i forgot remeber the code , there four wire from the unit such as white two . orange and blue , the follwoing connection where attemmed b

Hi,my coment is simple is just that i have design this circuit it works by switching on the relay which you said we could either use 5v or 12vdc.the problem i encounter here is that when the water reach the full level in the tank instead to off the pump is still pumping the water every where is been flooded….i built this project as you instruct…
pls i need to know the polarity of the IC NE555 kindly send me the legs number pls i need a details that can make the pump off..

hi expert…
may i know how to create the circuit to send the signal through wireless?is there any need for us to add the antenna in the circuit?
has anyone have a n experience to build a water leakage wireless sensor circuit before?really appreciate if anyone can share any information regarding this problem…

Hi Ravi Both probes C and A to be interchanged. C is just to say the electronics is OK with D3 comming on (to indicate also the tank circuit is also healthy and level is minimum). Now read the above description you can understand better. Q2 will start the pumpamd Q1 will stop the pump. Q3 is only for indication nothing to do with automation.

Yes I am also make one like this using float…it is semi automatic…..not fully automatic..It will switch off pump automatically need to make fully automatic How…????? and also need low voltage cutoff other wise it will damage water pump..

I am using a float on a vertical aluminium rod with two 4″ diameter aluminium discs (one for the upper limit and the lower one around one foot below).A mechanical switch with a lever (a kind of ‘limit switch’)is placed in between.When the water level goes down, the foat and discs go down. when the lower disc touches and pushes the switch lever,the switch turns ON and the pump starts.When the water level goes up, the float and the disc assembly goes up until the top disc pushes up the switch lever making the switch OFF and thereby the pump. I am using the mechanism for many years without any problem so far.Only thing is that we have to protect the switch from rain and hot sun.

Good circuit, But need change or clean the level sensing conductor frequently..It is directly contact with water.. It is a demerit of this kind of Water level controller….please publish a water level controller with float…